One of my favorite things to do with students in the late fall is to take them outside and point first to the Orion nebula, then to the Pleiades, and finally to the Hyades cluster, saying “these are snap shots in the evolution of open clusters.” Each of these systems is the home of young stars, but while the Orion nebula is very much a stellar nursery, with stars just 10 million years old or younger, the Pleiades, is more like a day care center with stars 100 million years old or younger. At the same time, Hyades is more like an afterschool program for stars 730 million years old or younger. All these systems are filled with celestial children. In their youth these stars still gather in clumps. But, as they age, the stars will drift apart until, as...

There are certain themes that arise in Astronomy Cast comments and fanmail. Most of the themes are happy, good, warm fuzzies. There are also your typical cranks. There are also, in the humorous category, a regular stream of well-meaning, highly hopeful people saying my mind isn’t open enough who accuse me of not talking to the right experts. I actually laughed loudly enough to scare the dog when I read the following earlier today from here: Please! Get your facts straight, people! Your original assumption is faulty, the Sun does not need to heat up and expand in a billion years, it will not “run out of fuel” in a billion years. The reason the Sun is predicted to heat up and expand in a billion years, is not lack of fuel, but the interference of...